Compound Interest Calculator
Project how your savings could grow with compound interest. Adjust for ongoing contributions, fees, and inflation, then compare with an optional second scenario to visualise different strategies side-by-side.
How the calculation works
- Management fees reduce the annual return before compounding, so you see the rate you actually receive.
- Inflation shows the future value in today’s money, giving you both nominal and real balances.
- Scenario B is pre-populated to demonstrate a comparison — tweak or clear the fields if you only need one scenario.
Scenario A highlights
Nominal vs real- Nominal final value
- £91,044.02
- Real final value
- £74,687.80
- Total invested
- £70,000.00
- Total interest (nominal)
- £21,044.02
Scenario B highlights
Comparison- Nominal final value
- £174,042.41
- Real final value
- £118,514.41
- Total invested
- £137,600.00
- Total interest (nominal)
- £36,442.41
Growth over time
Tracks the cumulative balance at the end of each year. Hover over the chart to compare balances between scenarios.
Keep in mind
Returns seldom arrive evenly, and this calculator assumes consistent monthly contributions and smooth compounding. Use the results as a planning guide only and consult a qualified advisor for personalised investment advice.
Buying a property? Estimate purchase taxes with the Stamp Duty Calculator.
Frequently asked questions
What is compound interest?
Compound interest is interest calculated on both the original amount invested and the interest already earned, so returns build on themselves over time rather than growing at a flat rate.
How does compounding frequency affect my results?
More frequent compounding, such as monthly rather than annually, produces a slightly higher final balance for the same annual rate, because interest is added to the balance more often and starts earning its own interest sooner.
Why does inflation reduce my real return?
Inflation erodes the purchasing power of money over time. The real final value shows what your nominal balance is worth in today’s money after accounting for the inflation rate you enter.
What’s a realistic annual return to assume?
This varies by asset class and risk tolerance. Many long-term diversified equity portfolios have historically returned 5–8% before fees, while cash and bonds are typically lower. Use a conservative estimate and stress-test with a lower rate.